The demand for further miniaturization of electronic devices, which is expected to lead the today´s CMOS based technology to its practicable and physical limit within the next ten to twenty years (ITRS), triggers an intense research in the field of "Molecular Electronics". Using molecules as building blocks in electronic devices will be promising due to several reasons. Conduction processes in molecular units involve only few to single electrons. This would lower the energy consumption to a minimum. Molecules or molecular building blocks can be chemically tailored with respect to their size, structure and electronic properties (e.g. wire, diode, switch). Furthermore, utilizing self-organization processes for the bottom-up fabrication of devices would significantly lower the fabrication costs. Nevertheless, implementing molecular units into electronic devices working with the same robustness and reliability such as the CMOS-based devices will be a great challenge. Several obstacles have to be overcome, as the detailed understanding of charge transport processes as well as controllable and reliable connecting of the molecules to the macroscopic “outer” world. All this requires a highly interdisciplinary research, involving chemists, physicists, materials scientists and engineers.

This scenario embodies the scientific background of the Virtual Insitute of Functional Molecular Systems for Information Technology (IFMIT). IFMIT was founded in 2004 within the framework of the Initiative and Networking Fund of the Helmholtz Association. The following groups of the RWTH Aachen University and  the Research Center Jülich collaborate within this framework on research topics that are related to basic questions of charge transport properties of functional molecules:

• The group of Prof. Ulrich Simon, Institute of Inorganic Chemistry, RWTH Aachen University, is concerned with the synthesis of functional molecules and ligand stabilized metal nanoparticles.
  
  
  
  

• The group of Prof. Maarten Wegewijs (Prof. Herbert Schoeller), Institute of Theoretical Physics A, RWTH Aachen University, is concerned with theoretical calculations.
  
  
• The group of Dr. Silvia Karthäuser (Prof. Dr. Reiner Waser) investigates charge transport characteristics of functional molecules by scanning probe techniques in UHV (UHV-STM/STS).
  
  

  		50x50nm² scan of BP4 inserted into an higly ordered SAM of dodecanethiol (C12). Bright spots represent single BP4 molecules.

  
  
• The group of  Prof. Thomas Wandlowski investigates structural and charge transport characteristics of functional molecules by electrochemical based scanning tunneling techniques ("electrochemical based break-junction" setup).  
  
  
  
  

  Principle of the electrochemical single molecule stretching experiment: (A) disabling of the STM feedback at a relative distance zo (defined by io = 100 pA and (EWE1 – EWE2) = 0.10 V) and approach; (B) formation of molecular junctions; (C) stretching with a constant pulling rate of 6 nm s-1; (D) breaking of the contact and switching on the feedback control.[8]
  The statistical analysis of up to 3000 individual pulling curves yields the values of the single junction conductance.